Head-mounted display device

ABSTRACT

A display device including a display panel including a planar portion and a curved portion extending from the planar portion, a controller to provide a data signal representing an image to be displayed on the planar portion and the curved portion to the display panel, in which the controller is configured to provide a data signal representing an image that is reduced at a greater extent to a portion of the curved portion that is disposed further away from the planar portion, and the display device is a head-mounted display device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/161,072, filed on Oct. 16, 2018, which claims priority from and thebenefit of Korean Patent Application No. 10-2018-0001449, filed on Jan.5, 2018, each of which is hereby incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND Field

Exemplary embodiments relate to a head-mounted display device, and moreparticularly, to a head-mounted display device having an improvedviewing angle.

Discussion of the Background

Head-mounted display devices are a head-worn device, which may include adisplay panel or be coupled to a display panel. The head-mounted displaydevices may be used to implement augmented reality or virtual reality. Ahead-mounted display device for realizing augmented reality may providea virtual graphic image through a semitransparent display. In this case,a user may visually recognize a virtual graphic image and an actualobject at the same time. The head-mounted display device forimplementing virtual reality provides a virtual graphic image to theuser's eyes. The user may experience the virtual reality through virtualcontents.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Devices constructed according to exemplary implementations of theinvention are capable of providing an improved viewing angle.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

A head-mounted display device according to an exemplary embodimentincludes a display panel including a planar portion and a curved portionextending from the planar portion, a controller to provide a data signalrepresenting an image to be displayed on the planar portion and thecurved portion to the display panel, and a case part on which thedisplay panel is mounted, in which the controller is configured toprovide a data signal representing an image that is reduced at apredetermined ratio to the curved portion, as compared with the planarportion.

The head-mounted display device may further include a cushion partdisposed between the case part and a wearer, and a strap part coupled tothe case part, in which the case part, the cushion part, and the strappart may define a viewing point of the wearer with respect to thedisplay panel.

The head-mounted display device may further include a sensor to measurethe viewing point of the wearer with respect to the display panel.

The curved portion may include first curved portions disposed onopposite sides of the planar portion in a first direction, and thecontroller may provide a data signal representing an image that isreduced in the first direction to the first curved portions.

The controller may provide a data signal representing an image that isreduced in a second direction substantially perpendicular to the firstdirection to the first curved portions.

The curved portion further may include second curved portions disposedon opposite sides of the planar portion in a second directionsubstantially perpendicular to the first direction, and the controllermay provide a data signal representing an image that is reduced in thesecond direction to the second curved portions.

The controller may provide a data signal representing an image that isreduced in the first direction to the second curved portions.

The first curved portions and the second curved portions may be spacedapart from each other at a corner of the planar portion.

The corner of the planar portion may not be visually recognized by thewearer.

The first curved portions and the second curved portions may beconnected to each other.

The controller may provide a data signal representing an image that isreduced at a greater extent to a portion of the curved portion that isdisposed further away from the planar portion.

The ratio of the entire curved portion may be A/L, where “A” is a lengthof the curved portion in the first direction and “L” is a length of anequivalent area of the curved portion in the first direction, and theequivalent area may be on a virtual plane extending from the planarportion, and provides a viewing angle substantially the same as aviewing angle of the curved portion in the first direction when viewedfrom the wearer's viewing point.

The reduced image may be substantially the same as an image that is notreduced on a virtual plane extending from the planar portion, whenviewed from the wearer's viewing point.

One side of the curved portion may contact the planar portiontangentially.

The ratio of the entire curved portion may be A/L, which is representedas the following Equation,

$\begin{matrix}{{\frac{A}{L} = \frac{\theta\left\lbrack {1 - {\left( {R/D} \right)\left( {1 - {\cos\;\theta}} \right)}} \right\rbrack}{{\left( {B/D} \right)\left( {1 - {\cos\;\theta}} \right)} + {\sin\;\theta}}},} & \lbrack{Equation}\rbrack\end{matrix}$

where “R” is a radius of curvature of the curved portion, “θ” is acentral angle of the curved portion, “D” is a distance between theviewing point of the wearer and the planar portion, and “B” is adistance in the first direction between a normal line of the planarportion that passes through the viewing point and a point where theplanar portion and the curved portion meet.

The ratio may be about 1 at a boundary between the planar portion andthe curved portion and decreases at a greater ratio as is disposedfurther away from the planar portion.

Another side of the curved portion may be perpendicular to a line ofsight of the wearer.

The ratio of the entire curved portion may be A/L, which is representedas the following Equation,

$\begin{matrix}{{\frac{A}{L} = \frac{\theta}{\tan\;\theta}},} & \lbrack{Equation}\rbrack\end{matrix}$

where “θ” is a central angle of the curved portion.

The head-mounted display device may further include an optical systemspaced apart from the display panel by a predetermined distance.

The display panel may include a left eye display area and a right eyedisplay area arranged in a left and right direction with respect to thewearer, and each of the left eye display area and the right eye displayarea may include a planar portion and a curved portion.

The display panel may include a left eye display panel and a right eyedisplay panel arranged in the left and right direction with respect tothe wearer, and each of the left eye display panel and the right eyedisplay panel may include a planar portion and a curved portion.

The left eye display panel and the right eye display panel may beseparated by a protrusion disposed therebetween.

Each of the curved portions of the left eye display panel and the righteye display panel may include a left curved portion disposed on a leftside of the planar portion and a right curved portion disposed on aright side of the planar portion.

The left curved portion and the right curved portion may havesubstantially the same length in the left and right direction.

The left curved portion and the right curved portion may have differentlengths in the left and right direction.

The left curved portion of the left eye display panel may be longer inthe left and right direction than the right curved portion of the lefteye display panel, and the right curved portion of the right eye displaypanel may be longer in the left and right direction than the left curvedportion of the right eye display panel.

An equivalent area of the right curved portion of the left eye displaypanel and an equivalent area of the left curved portion of the right eyedisplay panel may contact each other, and the equivalent area of theleft or right curved portion may be on a virtual plane extending fromthe planar portion, and the curved portion and the equivalent area ofthe left or right curved portion may provide substantially the sameviewing angle in the left and right direction, when viewed from thewearer's viewing point.

An equivalent area of the right curved portion of the left eye displaypanel and an equivalent area of the left curved portion of the right eyedisplay panel may overlap each other, and the equivalent area of theleft or right curved portion may be on a virtual plane extending fromthe planar portion, and the curved portion and the equivalent area ofthe left or right curved portion may provide substantially the sameviewing angle in the left and right direction, when viewed from thewearer's viewing point.

Each of the curved portions of the left eye display panel and the righteye display panel may include upper and lower curved portions disposedon upper and lower sides of the planar portion.

A head-mounted display device according to another exemplary embodimentincludes a display panel including a planar portion and a curved portionextending from the planar portion, and a case part on which the displaypanel is seated, in which the curved portion is configured to display animage that is reduced as compared with an image displayed on the planarportion.

The curved portion may have a resolution higher than that of the planarportion.

The display panel may include a plurality of gate lines, a plurality ofdata lines crossing the gate lines, and a plurality of pixels defined bythe gate lines and the data lines, in which the number of pixels perunit area in the curved portion may be greater than the number of pixelsper unit area in the planar portion.

An interval between the gate lines in the curved portion may decrease,as is disposed further away from the planar portion.

An interval between the data lines in the curved portion may decrease,as is disposed further away from the planar portion.

An area of each of the pixels disposed in the curved portion may becomesmaller, as a position thereof is further away from the planar portion.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention, and together with the description serve to explain theinventive concepts.

FIG. 1 is a block diagram of a head-mounted display device according toan exemplary embodiment.

FIG. 2A is a perspective view of a head-mounted display device accordingto an exemplary embodiment.

FIG. 2B is a view illustrating the use of a head-mounted display deviceaccording to an exemplary embodiment.

FIG. 3 is an exploded perspective view of a part of a head-mounteddisplay device according to an exemplary embodiment.

FIG. 4 is a schematic cross-sectional view of a head-mounted displaydevice according to an exemplary embodiment.

FIGS. 5A and 5B are schematic cross-sectional views of a display panelaccording to exemplary embodiments.

FIGS. 6A and 6B are a front view and a side view of a display panel,respectively, according to exemplary embodiments.

FIGS. 7A and 7B are views illustrating a non-reduced image and a reducedimage, respectively, according to exemplary embodiments.

FIG. 8 is an explanatory view illustrating conversion of an imagedisplayed on a curved portion according to an exemplary embodiment.

FIG. 9 is a schematic cross-sectional view of an optical systemaccording to an exemplary embodiment.

FIG. 10 is a schematic perspective view of a separated binocularhead-mounted display device according to an exemplary embodiment.

FIG. 11 is a schematic cross-sectional view of a separated binocularhead-mounted display device according to an exemplary embodiment.

FIG. 12 is a schematic cross-sectional view of a separated binocularhead-mounted display device according to an exemplary embodiment.

FIG. 13A is a schematic perspective view of an integrated binoculardisplay panel according to an exemplary embodiment.

FIGS. 13B and 13C are cross-sectional views of the integrated binoculardisplay panel of FIG. 13A.

FIG. 14 is a schematic perspective view of a separated binocular displaypanel according to an exemplary embodiment.

FIGS. 15A and 15B are schematic development views illustrating anintegrated binocular display panel according to an exemplary embodiment.

FIG. 16 is a schematic development view illustrating a separatedbinocular display panel according to an exemplary embodiment.

FIG. 17 is an enlarged view a part of a display panel according to anexemplary embodiment.

FIG. 18 is a cross-sectional view taken along line IV-IV′ of FIG. 4.

FIGS. 19A and 19B are development views of a display panel according toexemplary embodiments.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations ofimplementations of the invention. As used herein “embodiments” and“implementations” are interchangeable words that are non-limitingexamples of devices or methods employing one or more of the inventiveconcepts disclosed herein. It is apparent, however, that variousexemplary embodiments may be practiced without these specific details orwith one or more equivalent arrangements. In other instances, well-knownstructures and devices are shown in block diagram form in order to avoidunnecessarily obscuring various exemplary embodiments. Further, variousexemplary embodiments may be different, but do not have to be exclusive.For example, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the D1-axis, the D2-axis,and the D3-axis are not limited to three axes of a rectangularcoordinate system, such as the x, y, and z-axes, and may be interpretedin a broader sense. For example, the D1-axis, the D2-axis, and theD3-axis may be perpendicular to one another, or may represent differentdirections that are not perpendicular to one another. For the purposesof this disclosure, “at least one of X, Y, and Z” and “at least oneselected from the group consisting of X, Y, and Z” may be construed as Xonly, Y only, Z only, or any combination of two or more of X, Y, and Z,such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should notnecessarily be construed as limited to the particular illustrated shapesof regions, but are to include deviations in shapes that result from,for instance, manufacturing. In this manner, regions illustrated in thedrawings may be schematic in nature and the shapes of these regions maynot reflect actual shapes of regions of a device and, as such, are notnecessarily intended to be limiting.

As customary in the field, some exemplary embodiments are described andillustrated in the accompanying drawings in terms of functional blocks,units, and/or modules. Those skilled in the art will appreciate thatthese blocks, units, and/or modules are physically implemented byelectronic (or optical) circuits, such as logic circuits, discretecomponents, microprocessors, hard-wired circuits, memory elements,wiring connections, and the like, which may be formed usingsemiconductor-based fabrication techniques or other manufacturingtechnologies. In the case of the blocks, units, and/or modules beingimplemented by microprocessors or other similar hardware, they may beprogrammed and controlled using software (e.g., microcode) to performvarious functions discussed herein and may optionally be driven byfirmware and/or software. It is also contemplated that each block, unit,and/or module may be implemented by dedicated hardware, or as acombination of dedicated hardware to perform some functions and aprocessor (e.g., one or more programmed microprocessors and associatedcircuitry) to perform other functions. Also, each block, unit, and/ormodule of some exemplary embodiments may be physically separated intotwo or more interacting and discrete blocks, units, and/or moduleswithout departing from the scope of the inventive concepts. Further, theblocks, units, and/or modules of some exemplary embodiments may bephysically combined into more complex blocks, units, and/or moduleswithout departing from the scope of the inventive concepts.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

FIG. 1 is a block diagram of a head-mounted display device according toan exemplary embodiment. The head-mounted display device according to anexemplary embodiment may include an image processor 10, a display unit20, a controller 30, a communication unit 40, a storage unit 50, and auser input unit 60.

The image processor 10 may perform various image processing processes,and the type of the image processing processes performed by the imageprocessor 10 is not particularly limited. For example, the imageprocessor 10 may perform de-multiplexing for distributing apredetermined signal to each characteristic signal, decoding accordingto the image format of the image signal, de-interlacing for convertingan interlaced image signal into a progressive mode, noise reduction forimproving image quality, detail enhancement, conversion of a framerefresh rate, or the like. In addition, the image processor 10 mayinclude a decoder, which may decode a source image corresponding to theimage format of the encoded source image, and a frame buffer, which maystore the decoded source image on a frame-by-frame basis.

The image processor 10 may be implemented as a system-on-chip (“SOC”),through which the aforementioned functions are integrated, or as animage processing board, through which individual components capable ofindependently performing each of the aforementioned processes aremounted on a printed circuit board.

The image processor 10 may perform various predetermined imageprocessing processes for a broadcast signal including an image signalreceived from the communication unit 40, and a source image including animage signal received from an image source. The image processor 10 mayoutput the processed image signal to the display unit 20, such that theprocessed source image may be displayed on the display unit 20. Theimage processor 10 (or the controller 30 to be described below) mayperform a process so that the image may be reduced to be displayed on acurved portion, which will be described in more detail below.

The display unit 20 may display images based on an image signal outputfrom the image processor 10. The display unit 20 may include a displaypanel 200, on which images are displayed, and a panel driver forprocessing the input image signal to display the image on the displaypanel. However, the inventive concepts are not limited thereto, andvarious methods of implementing images may be applicable. The imagesignal received from an external input source through an interface maybe displayed on the display unit 20 through image processing processes,such as decoding, deinterlacing, scaling, or the like.

The controller 30 may control the overall configuration inside thehead-mounted display device. The controller 30 may be separated from orintegrated with the image processor 10.

The communication unit 40 may receive a signal of an external input andtransmit the signal to the image processor 10 or the controller 30. Thecommunication unit 40 may be connected to various external input cablesto receive a signal from a corresponding external input by wire orwirelessly according to a predetermined wireless communication standard.

The communication unit 40 may include a plurality of connectors, towhich the respective cables are individually connected. Thecommunication unit 40 may receive a signal from a connected externalinput, for example, a HDMI signal, a USB signal, a broadcast signalaccording to the specification of the component, an image signal, a datasignal, or the like, or may receive a communication data through acommunication network.

The communication unit 40 may include various additional configurations,such as a wireless communication module for wireless communication or atuner for tuning a broadcast signal, in addition to the configurationsthat receive signals/data from an external input. The communication unit40 may also transmit the information/data/signal of the head-mounteddisplay device to an external device. That is, the communication unit 40may not be limited to a configuration for receiving a signal from anexternal device, but may be implemented as an interface capable ofbidirectional communication. The communication unit 40 may receive acontrol signal for selecting a user interface (UI) from a plurality ofcontrol devices. The communication unit 40 may include a communicationmodule for publicly known short range wireless communication, such asBluetooth, infrared (“IR”), ultra wideband (“UWB”), Zigbee®, or thelike, or may include a publicly known communication port for wiredcommunication. The communication unit 40 may be used for variouspurposes, such as receiving a command for operating the display,transmission/reception of data, and the like, in addition to the controlsignal for selecting a UI.

The storage unit 50 may be provided as a writeable nonvolatile memory(e.g., a writable ROM), so that data may remain on the head-mounteddisplay device even when the power is turned off, and may reflectchanges of the user. For example, the storage unit 140 may include oneof a flash memory, an EPROM, or an EEPROM.

The user input unit 60 may transmit various preset control commands orinformation to the controller 30 according to a user's operation andinput. The user input unit 60 may be implemented by a menu-key or aninput panel provided outside the head-mounted display device, or aremote controller separated from the head-mounted display device.

The user input unit 60 may receive the user's motion and voice. Theuser's motion may include a touch input. The user input unit 60 maydirectly receive the user's motion and voice, or may receive informationof the user's motion and voice from an external device.

In addition, the user input unit 60 may include a display panel 200 (seeFIG. 3), an optical system 400 (see FIG. 3), and an adjustor capable ofadjusting a distance of the user's viewing point. The adjustor may movethe position of the display panel 200 and/or the optical system 400 inforward or backward direction (a Z-axis direction in FIG. 3) from theuser's point of view according to the user's operation.

In addition, the user input unit 60 may include a sensor capable ofmeasuring the user's viewing point. A reduction ratio of an imagedisplayed on a curved portion 220 of the display panel 200 (see FIG. 4),to be described below, may be changed according to the measured user'sviewing point and the distance of the display panel 200.

FIG. 2A is a perspective view of a head-mounted display device accordingto an exemplary embodiment, and FIG. 2B is a view illustrating the useof a head-mounted display device according to an exemplary embodiment.

Referring to FIGS. 2A and 2B, the head-mounted display device HMD is adevice worn on the head of a user 500. The head-mounted display deviceHMD may provide an image while the actual peripheral vision of the user500 may be blocked or substantially blocked. The user 500 wearing thehead-mounted display device HMD may be more easily immersed into thevirtual reality.

The head-mounted display device may include a case part 100, a cushionpart 300, and a strap part 350.

The case part 100 may be worn on the head of the user 500. The displaypanel 200 (see FIG. 3) for displaying images, an acceleration sensor,and the like may be accommodated in the case part 100. The accelerationsensor senses the motion of the user 500 and may transmit apredetermined signal to the display panel 200. Accordingly, the displaypanel 200 may provide an image that corresponds to the change of the eyesight of the user 500. Accordingly, the user 500 may experience virtualreality similar to the actual reality.

In the case part 100, components having various functions other thanthose described above may be accommodated. For example, the imageprocessor 10, the display unit 20, the controller 30, the communicationunit 40, the storage unit 50, and the user input unit 60 described abovemay be accommodated therein.

The cushion part 300 may be disposed between the case part 100 and thehead of the user 500. The cushion part 300 may include a material thatis deformable in its shape. For example, the cushion part 300 mayinclude a polymer resin (e.g., polyurethane, polycarbonate,polypropylene, and polyethylene), a liquid rubber, a urethane-basedmaterial, or a sponge formed by foam-molding an acrylic-based material.However, the inventive concepts are not limited thereto, and the cushionpart 300 may include various other materials.

The cushion part 300 may allow the case part 100 to be in close contactwith the user 500 and improve the comfort of the user 500. The cushionpart 300 may be detachable from the case part 100. In an exemplaryembodiment, the cushion part 300 may be omitted.

The strap part 350 may be combined with the case part 100 so that thecase part 100 may be easily worn by the user 500. The strap part 350 mayinclude a main strap 351 and an upper strap 352.

The main strap 351 may be worn along the circumference of the head ofthe user 500. The main strap 351 may secure the case part 100 to theuser 500 so that the case part 100 may be brought into close contactwith the head of the user 500. The upper strap 352 may connect the casepart 100 to the main strap 351 along an upper portion of the head of theuser 500. The upper strap 352 may substantially secure the case part 100to the user 500. In addition, the upper strap 352 may disperse the loadof the case part 100 to improve the wearing comfort of the user 500.

In FIG. 2A, the shapes of the main strap 351 and the upper strap 352 areshown as being adjustable in lengths, but the inventive concepts are notlimited thereto. For example, in another exemplary embodiment, the mainstrap 351 and the upper strap 352 may have elasticity, and the lengthadjustable portions may be omitted.

The strap part 350 may be variously modified from those shown in FIGS.2A and 2B, as long as the case part 100 is securely fixed to the user500. For example, in another exemplary embodiment, the upper strap 352may be omitted. In addition, in another exemplary embodiment, the strappart 350 may be transformed into various forms, such as a helmetcombined with the case part 100, or a pair of glasses coupled with thecase part 100.

FIG. 3 is an exploded perspective view of a part of a head-mounteddisplay device according to an exemplary embodiment. In FIG. 3, thestrap part 350 (see FIGS. 2A and 2B) is not illustrated for convenienceof description.

Referring to FIG. 3, the case part 100 may be divided into a body 101and a cover 102. A display panel 200 is disposed between the body 101and the cover 102, and the cover 102 may cover a space where the displaypanel 200 is seated. FIG. 3 shows that the body 101 and the cover 102are separated from each other, but the inventive concepts are notlimited thereto. For example, as illustrated in FIG. 4, the body 101 andthe cover 102 may be provided unitarily and may not be separated fromeach other.

The display panel 200 may be disposed between the body 101 and the cover102. The display panel 200 may be unitarily embedded in the head-mounteddisplay device to provide images, but the inventive concepts are notlimited thereto. For example, a display device (e.g., a portableterminal) including the display panel 200 may be combined with thehead-mounted display device to provide images.

In FIG. 3, a left eye image and a right eye image are displayed througha single display panel 200 (e.g., a binocular integration type) as anexample. The display panel 200 may be divided into a left eye imagedisplay area 201, in which the left eye image is displayed, and a righteye image display area 202, in which the right eye image is displayed.The left eye image display area 201 and right eye image display area 202may be driven by separate panel drivers, respectively. However, theinventive concepts are not limited thereto, and both the left eye imagedisplay area 201 and the right eye image display area 202 may be drivenby a single panel driver. In addition, as illustrated in FIG. 10,according to another exemplary embodiment, the display panel 200 mayinclude a left eye display panel 241 and a right eye display panel 242that are separated from each other. The specific shape of the displaypanel 200 will be described below.

The display panel 200 generates an image corresponding to the inputimage data. The display panel 200 may include any one of various typesof display panels, such as an organic light emitting diode (“OLED”)display panel, a liquid crystal display (“LCD”) panel, a plasma displaypanel, an electrophoretic display panel, and an electrowetting displaypanel. Hereinafter, the display panel 200 will be described as an OLEDdisplay panel, for example, but the inventive concepts are not limitedthereto. The detailed structure of the OLED display panel will bedescribed below with reference to FIGS. 17 and 18.

The optical system 400 may be disposed inside the body 101 of the casepart 100. The optical system 400 may be a convex aspherical lens. Inaddition, the optical system 400 may be a Fresnel lens, which is dividedinto several circular strap-shaped lenses to reduce the thickness of thelens. The optical system 400 may enlarge the image provided from thedisplay panel 200. The optical system 400 may be spaced apart from thedisplay panel 200 in a first direction (Z-axis direction). The opticalsystem 400 may be disposed between the display panel 200 and a user'seye 510 (see FIG. 4).

The optical system 400 may include a left eye optical system 401 and aright eye optical system 402. The left eye optical system 401 enlargesan image to provide the image to a left pupil 511 of the user 500 (seeFIG. 4), and the right eye optical system 402 enlarges the image toprovide the image to a right pupil 512 of the user 500 (see FIG. 4). Theleft eye optical system 401 and the right eye optical system 402 may bespaced apart from each other in left and right direction (X-axisdirection). A distance between the left eye optical system 401 and theright eye optical system 402 may be adjusted corresponding to a distancebetween the two eyes of the user 500 (see FIG. 2B).

FIG. 4 is a schematic cross-sectional view of a head-mounted displaydevice according to an exemplary embodiment, which is taken along lineI-I′ of FIG. 3. In FIG. 4, components other than the case part 100, thedisplay panel 200, the user's eye 510, and a user's face line 520 arenot illustrated. Hereinafter, a left and right direction (X-axisdirection), an up and down direction (Y-axis direction), and a front andback direction (Z-axis direction) are defined with respect to a line ofsight of the user 500 (hereinafter, “a wearer”) in a state in which thedisplay device is worn.

As illustrated in FIG. 4, left and right sides of the display panel 200is concavely curved with respect to a line of sight of the wearer 500.More specifically, the display panel 200 includes a central planarportion 210 and left and right curved portions 220. The planar portion210 is substantially flat. That is, the planar portion 210 has acurvature of about zero or substantially zero. The curved portion 220extends in the left and right direction from the planar portion 210. Ina cross-sectional view, a left curved portion 221 and a right curvedportion 222 are symmetrical with respect to a symmetry line 263 thatpasses through the center of the display panel 200, which isperpendicular to the display panel 200.

As used herein, unless otherwise stated, the planar portion 210 and thecurved portion 220 may refer to an area where images are displayed.

The curved portion 220 has a predetermined width in the left and rightdirection (X-direction) and a predetermined length in the up and downdirection (Y-direction). The width direction (Z-direction) has apredetermined curvature (which is defined as the inverse of the radiusof curvature) other than zero. The longitudinal direction may have acurvature of zero.

The case part 100 supports the display panel 200, so that the displaypanel 200 may maintain the curved state. The planar portion 210 issupported by the cover 102, and the curved portion 220 may be supportedby the body 101, which extends in the front and back direction(Z-direction).

FIG. 5A is a cross-sectional view for explaining a reduction ratio ofthe image displayed on the curved portion 220 in the left and rightdirection according to an exemplary embodiment, and corresponds to theright side of FIG. 4. As illustrated in FIG. 5A, according to anexemplary embodiment, a wider viewing angle may be provided with asmaller display panel 200.

FIG. 5A illustrates a part of the right side of the planar portion 210,the right curved portion 222, and the right eye (or pupil) 512 of theuser. As used herein, a point or a line described with reference to across-sectional view may refer to a line or a plane that passes throughthe point or the line, respectively, and is perpendicular to thecross-sectional view.

Referring to FIG. 5A, a virtual plane 230 is a plane extending from theplanar portion 210. As used herein, “D” represents a distance between aviewing point 420 of the right eye 512 of the user 500 and the virtualplane 230 or the planar portion 210 (or “D” represents a line normal tothe virtual plane 230). The distance D may have a predetermined valuedetermined according to the arrangement of the display panel 200 in thecase part 100, the structure of the cushion part 300, a refractive indexof the optical system 400, and the like. Alternatively, the distance Dmay be a value set by the user. Still alternatively, the distance D maybe a value measured by the above-described sensor.

As used herein, “R” is a radius of curvature of the curved portion 222.The center of the curved portion 222 is at a point where the planarportion 210 and the curved portion 222 meet, that is, at a startingpoint 422 of the curved portion 222 on a line normal to the displaypanel 200. More particularly, the curved portion 222 contacts thevirtual plane 230. As used herein, “θ” represents a central angle of thecurved portion 222. As used herein, “A” represents a width of the curvedportion 220 in the left and right direction, that is, a length of an arcof the curved portion 220 in the cross-sectional view of FIG. 5A.

As used herein, “B” represents a distance between the normal line D ofthe virtual plane 230 that passes through the viewing point 420 and thenormal line of the virtual plane 230 that passes through the startingpoint 422 of the curved portion 222.

Dotted lines 410 and 411 are straight lines that indicate the line ofsight from the viewing point 420 of the user 500. A dotted line 410 is astraight line that passes through the viewing point 420 and an end point421 of the curved portion 222, and a dotted line 411 is a straight linethat passes through the viewing point 420 and the starting point 422 ofthe curved portion 222 (or the virtual plane 230). An end point 423 onthe virtual plane 230 is a point where the virtual plane 230 intersectsthe dotted line 410.

As used herein, “L” represents a distance between the normal lines thatpass through the starting point 422 on the virtual plane 230 and the endpoint 423 on the virtual plane 230. A plane between the starting point422 on the virtual plane 230 and the end point 423 on the virtual plane230 is defined as an equivalent area 231 of the curved portion 222.

y:D=x: R(1−cos θ)  [Equation 1]

y−x=R sin θ+B  [Equation 2]

L=x+R sin θ  [Equation 3]

The length L of the equivalent area 231 is derived from the aboveEquations 1, 2, and 3, as illustrated below in Equation 4.

$\begin{matrix}{L = {\frac{{\left( {B/D} \right)\left( {1\ \cos\;\theta} \right)} + {\sin\;\theta}}{1\left( {R/D} \right)\left( {1 - {\cos\;\theta}} \right)}R}} & \left\lbrack {{Equation}\mspace{20mu} 4} \right\rbrack\end{matrix}$

In an exemplary embodiment, a length A of the curved portion isexpressed by the following Equation 5.

A=Rθ (θ in radian)  [Equation 5]

Accordingly, a left and right image reduction ratio A/L of the curvedportion with respect to the planar portion is expressed by the followingEquation 6.

$\begin{matrix}{\frac{A}{L} = \frac{\theta\left\lbrack {1 - {\left( {R/D} \right)\left( {1 - {\cos\theta}} \right)}} \right\rbrack}{{\left( {B/D} \right)\left( {1 - {\cos\theta}} \right)} + {\sin\theta}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

FIG. 5B is a cross-sectional view for explaining a reduction ratio ofthe image displayed on the curved portion 220 according to an exemplaryembodiment, and illustrates a curved portion having R and 0, which aredifferent from those of FIG. 5A.

As illustrated in FIG. 5B, a central point of the curved portion 222 islocated on the line of sight 410 that passes through the viewing point420 of the user 500 and the end point 421 of the curved portion 222.Accordingly, the line of sight 410 crosses the curved portion 222 at theend point 222 substantially perpendicularly. Other conditions aresubstantially the same as those described above with reference to FIG.5A. According to the illustrated exemplary embodiment, since L=R tan θ,the left and right image reduction ratio A/L of the curved portion 222with respect to the planar portion 210 is expressed by the followingEquation 7.

$\begin{matrix}{\frac{A}{L} = \frac{\theta}{\tan\;\theta}} & \left\lbrack {{Equation}\mspace{20mu} 7} \right\rbrack\end{matrix}$

In an exemplary embodiment, the image reduction ratio A/L of the curvedportion 222 with respect to the planar portion 210 is defined as a ratioof the size of a substantially same image displayed on the curvedportion 222 to that displayed on the planar portion 210. For example,when a size of an image displayed on the planar portion 210 is assumedas L1, and if the same image were displayed in the equivalent area 230,the size thereof would also be L1. However, when the same image isdisplayed on the curved portion 222, the size is reduced to L2.Accordingly, the image reduction ratio is L2/L1.

In an exemplary embodiment, the left and right image reduction ratios ofthe curved portion at each point of the curved portion 222 may all bethe same as A/L, or may be different according to their respectivepositions on the curved portion 222. For example, the left and rightimage reduction ratio at the starting point 422 of the curved portion222 may be 1. That is, the image is reduced at a same proportion as theplanar portion 210, and as the point moves farther away from thestarting point 422, the image may be reduced at a greater ratio. Inparticular, the image displayed on the curved portion 222 may be reducedat a greater extent, as its distance from the planar portion 210 isincreased. As used herein, the image being further reduced means thatthe ratio of the image of the curved portion 222 to the image of theplanar portion 210 (e.g., the image reduction ratio) is smaller.Although the image reduction ratio differs depending on its position onthe curved portion 222, the reduction ratio of the entire image of thecurved portion may be A/L.

For example, in the illustrated exemplary embodiment shown in FIG. 5B,the image reduction ratio dA/dL at an arbitrary point (a central angleθ) is represented by the following Equation.

$\begin{matrix}{\frac{dA}{dL} = {\frac{\frac{dA}{d\theta}}{\frac{dL}{d\theta}} = {\cos^{2}\theta}}} & \left\lbrack {{Equation}\mspace{20mu} 8} \right\rbrack\end{matrix}$

Accordingly, when θ=0, that is, at the boundary line 422 between theplanar portion 210 and the curved portion 222, the image reduction ratiois about 1. As θ increases, that is, as the distance from the planarportion 210 increases, the image reduction ratio decreases at a greaterratio.

FIG. 6A is a front view and FIG. 6B is a side view illustrating a partof a display panel according to an exemplary embodiment. An up and downreduction ratio will be described with reference to FIGS. 6A and 6B. Asdescribed above with reference to FIGS. 5A and 5B, the image displayedon the curved portion 220, which is disposed on the right and left sidesof the planar portion 210, may be reduced in the left and rightdirection. In addition, according to an exemplary embodiment, the imagedisplayed on the curved portion 220 may be reduced in the up and downdirection, as shown in FIGS. 6A and 6B.

For example, in the exemplary embodiments shown in FIGS. 5A and 5B, anup and down image reduction ratio W2/W1 at an arbitrary point (a centralangle θ) may be obtained by the following Equation 9.

D:D−R(1−cos θ)=W ₁ :W ₂  [Equation 9]

In Equation 9, “W2” is a length of the curved portion 222 in the up anddown direction, “W1” is a length in the up and down direction of theequivalent area 231 corresponding to the curved portion 222, “R (1−cosθ)” is a distance between an arbitrary point (a central angle θ) and theequivalent area 231, and “D” is a distance between the planar portion210 and the viewing point 420.

Accordingly, based on Equation 9, the up and down image reduction ratioW2/W1 may be obtained by the following Equation 10.

$\begin{matrix}{\frac{W_{2}}{W_{1}} = {1 - \frac{R\left( {1 - {\cos\;\theta}} \right)}{D}}} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

Accordingly, when θ=0, that is, at the boundary line 422 between theplanar portion 210 and the curved portion 222, the up and down imagereduction ratio is about 1. As θ increases, that is, as the distancefrom the planar portion 210 increases, the image reduction ratiodecreases at a greater ratio.

FIG. 7A is a view illustrating a non-reduced image, and FIG. 7B is aview illustrating a reduced image, according to an exemplary embodiment.

According to an exemplary embodiment, the communication unit 40 or thestorage unit 50 provides a data of an image illustrated in FIG. 7A tothe controller 30 or the image processor 10 (hereinafter, may becollectively referred to as “a controller 30”). The controller 30 mayconvert the data of the image illustrated in FIG. 7A into a data of areduced image illustrated in FIG. 7B. However, the inventive conceptsare not limited thereto, and the communication unit 40 or the storageunit 50 may provide a data of an image, which has been reduced inadvance as in FIG. 7B, and the controller 30 may provide the data of thereduced image illustrated in FIG. 7B to the display unit 20.

As illustrated in FIG. 7A, in general, images are configured to bedisplayed on a flat display panel, and each portion of the displaypanel, for example, the central portion and the peripheral portion ofthe display panel may display images at the same ratio. Accordingly, ifan image for a flat surface (hereinafter, “flat image”) illustrated inFIG. 7A is displayed on the curved portion 220 of the display panel 200as shown FIG. 4, the image may be distorted. Accordingly, thehead-mounted display device according to an exemplary embodimentdisplays images that are reduced in the left and right direction and/orthe up and down direction on the curved portion 220, as describedhereinabove with reference to FIGS. 5A to 6B.

A flat image Im illustrated in FIG. 7A includes partial images Im (i, j)each having substantially the same size. All of the partial images Im(1, 1) . . . Im (i, j) . . . Im (16, 8) may be displayed on the displaypanel at the same rate. The flat image Im may be an original image.Alternatively, the original image may be an image that is entirelyscaled at the same rate for each partial image Im (i, j) by thecontroller 30, according to the size of the planar portion 210 and theequivalent area 231.

The controller 30 may determine the partial image Im (i, j) to bedisplayed on the planar portion 210 and the partial image Im (i, j) tobe displayed on the equivalent area 231 (the curved portion 220). Thecontroller 30 partially reduces the partial image Im (i, j) of theequivalent area 231 in the left and right direction and/or the up anddown direction.

As illustrated in FIG. 7B, the partial image Im (i, j) of the equivalentarea 231 are further reduced in the left and right direction and the upand down direction, as they are further spaced away from the planarportion 210. The data for the partially reduced image Im′ is provided tothe panel driver of the display unit 20, and the panel driver displaysthe image Im′ illustrated in FIG. 7B on the display panel 200.

Accordingly to an exemplary embodiment, the image Im′, as shown in FIG.7B, displayed on the curved portion 220 may be viewed to besubstantially the same as the image Im, as shown in FIG. 7A, displayedon the virtual plane 230 or the equivalent area 231 extending from theplanar portion 210. In this manner, an exemplary embodiment of thepresent invention may provide a wider viewing angle to the user, whileusing a relatively small display panel. In addition, the distortion ofthe image of FIG. 7A may be significantly suppressed, as the image isdisplayed on a general flat display panel.

FIG. 8 is an explanatory view illustrating a conversion of an imagedisplayed on a curved portion according to an exemplary embodiment.

As described above, the curved surface image Im′ (hereinafter, “curvedimage”) displayed on the curved portion 220 according to an exemplaryembodiment may be viewed to be substantially the same as the flat imageIm displayed on the equivalent area 231 extending from the planarportion 210.

Referring to FIG. 8, one point of the curved portion 220 and one pointof the equivalent area 231, through which one straight line passes fromthe viewing point 420, correspond to each other, and substantially thesame image may be displayed on the two points that correspond to eachother. Accordingly, a partial image Im′ (i, j) that corresponds to apartial image Im (i, j) at the one point of the equivalent area 231 isdisplayed at the corresponding one point of the curved portion 220. Inaddition, as described above, the curved partial image Im′ (i, j) may bereduced in the left and right direction and the up and down direction.

Although FIG. 8 shows a curved portion has a partial cylinder shape, theinventive concepts are not limited thereto. The image conversion methoddescribed with reference to FIG. 8 may be applied to a curved portionhaving an arbitrary shape.

In addition, although FIGS. 4 to 8 show the curved portion 220 isdisposed on the right and left sides of the planar portion 210, theinventive concepts are not limited thereto. The exemplary embodimentsdescribed with reference to FIGS. 4 to 8 may be equally applied to thecurved portion disposed on the upper and lower sides of the planarportion 22.

FIG. 9 is a schematic cross-sectional view of an optical systemaccording to an exemplary embodiment, and shows refraction of the lineof sight by the optical system 400. Although FIG. 9 is described withrespect to the right eye optical system 402, it may be similarly appliedto the left eye optical system 401 (see FIG. 3).

As illustrated in FIG. 9, lines of sight 412 and 413 from an actualviewing point 430 of the user are refracted while passing through theoptical system 400. Accordingly, in the descriptions with reference toFIGS. 5A and 5B, the lines of sight 410 and 411 viewing the curvedportion 222 and the equivalent area 230 may not form a straight linewith the actual viewing point 430 of the user 500.

In an exemplary embodiment, a refractive index n of the optical system400 is expressed by the following Equation 11.

$\begin{matrix}{n = \frac{\sin\theta_{1}}{\sin\theta_{2}}} & \left\lbrack {{Equation}\mspace{20mu} 11} \right\rbrack\end{matrix}$

In FIG. 9, “OL” is a distance between the planar portion 210 and theright eye optical system 402, “D′” a distance between the planar portion210 and the actual viewing point 430 of the user 500, “D” is a distancebetween the planar portion 210 and the virtual viewing point 420 of thelines of sight 410 and 411 that pass through the curved portion 222.

Accordingly, when the head-mounted display device according to anexemplary embodiment includes the optical system 400, the aforementionedviewing point 420 refers to the virtual viewing point 420, rather thanthe actual viewing point 430 of the user, and “D” used in the Equations1 to 7 refers to a distance D to the virtual viewing point 420, ratherthan a distance D′ to the actual viewing point 430 of the user.

The distance D to the virtual viewing point 420 may be determinedaccording to the distance D′ to the actual viewing point 430 of the user500 and the refractive index of the right eye optical system 402.

FIG. 10 is a schematic perspective view of a separated binocularhead-mounted display panel 240 according to an exemplary embodiment.FIG. 11 is a cross-sectional view of FIG. 10. Detailed descriptions ofsubstantially the same elements described above will be omitted to avoidredundancy.

As illustrated in FIG. 10, the display panel 240 according to anexemplary embodiment includes a left eye display panel 241 and a righteye display panel 242.

As illustrated in FIGS. 10 and 11, the display panels 241 and 242 arecurved on the left and right sides with respect to the line of sight ofthe user 500. More specifically, the left eye display panel 241 includesa planar portion 251L at the central portion and curved portions 262Land 261L on the left and right sides of the planar portion 251L. Theplanar portion 251L is substantially flat. That is, the planar portion251L has a curvature of about zero or substantially zero. The curvedportion 260L extends in the left and right direction from the planarportion 251L. The curved portion 260L has a predetermined width in theleft and right direction and a predetermined length in the up and downdirection. The width direction has a predetermined curvature (which isdefined as the inverse of the radius of curvature) other than zero. Thelongitudinal direction may have a curvature of zero.

In the cross-sectional view of the left eye display panel 241 accordingto an exemplary embodiment, the curved portion 262L on the left side andthe curved portion 261L on the right side are symmetrical with respectto a symmetry line that passes through the center of the left eyedisplay panel 241, which is perpendicular to the left eye display panel241. The left eye display panel 241 and the right eye display panel 242are symmetrical with respect to the symmetry plane 263 that passesthrough the center therebetween, which is perpendicular to the left eyedisplay panel 241.

The case part 100 supports the display panel 240 so that the displaypanel 240 may maintain the curved state. In addition, the case part 100may further include a protrusion 103, which separates the two displaypanels 241 and 242 and supports the right curved portion 261L of theleft eye display panel 241 and the left curved portion 262L of the righteye display panel 242. The protrusion 103 may block the view of each eyeso that the left eye display panel 241 may not be viewed from the righteye 512, and the right eye display panel 242 may not be viewed from theleft eye 511. In the following, the description will be focused on theleft eye display panel 241, but the same may be applied to the right eyedisplay panel 242 as well.

FIG. 12 is a schematic cross-sectional view of a separated binocularhead-mounted display device according to an exemplary embodiment.

The image reduction ratio of the curved portion with respect to theplanar portion described hereinabove with reference to FIGS. 5A and 5Bmay be applied to the illustrated exemplary embodiment, and thus,repeated descriptions thereof will be omitted to avoid redundancy.

The left curved portion 262L and the right curved portion 261L of theleft eye display panel 241 have the same radius of curvature R. However,the inventive concepts are not limited thereto, and the left curvedportion 262L and the right curved portion 261L may have different radiiof curvature.

In addition, the left curved portion 262L and the right curved portion261L have central angles θ3 and θ1, respectively. The central angles θ3and θ1 may be substantially equal to each other, or may be differentfrom each other. For example, the central angle θ3 may be larger thanthe central angle θ1 in order to secure the left viewing angle of theleft eye 511 to be greater than the right viewing angle.

In an exemplary embodiment, an area of the right curved portion 261Lwhere the image is displayed may be changed. For example, the image maybe displayed on the entire curved portion 261L having the central angleθ1. Alternatively, according to exemplary embodiments, the image may bedisplayed only on a portion of the right curved portion 261L, that is,only the curved portion that has a central angle θ less than the centralangle θ1.

For example, the central angle θ of the area where the image isdisplayed may be determined according to the input of the user 500 andaccording to the type of the image to be displayed (e.g., 2D or 3Dimage). Accordingly, the length L2 of the equivalent area correspondingto the image displayed on the curved portion may be varied. Although thepresent example is described with reference to the right curved portion261L, the inventive concepts are not limited thereto, and it may also beapplicable to the left curved portion 262L.

For example, a central angle θ2 may be determined so that a sight ofline that passes through an end point of the curved portion having thecentral angle θ2 may meet the symmetry line 263 on the virtual plane230. Accordingly, the equivalent area L2 of the right curved portion261L of the left eye display panel 241 and the equivalent area (the areasymmetric to L2) of the left curved portion 262R of the right eyedisplay panel 242 may contact each other.

In an exemplary embodiment, the image may be displayed up to the centralangle θ1 that is larger than the central angle θ2. Accordingly, theequivalent area L1 of the right curved portion 261L of the left eyedisplay panel 241 and the equivalent area (the area symmetric to L1) ofthe left curved portion 262R of the right eye display panel 242 mayoverlap each other. Accordingly, the separated binocular display panelaccording to the illustrated exemplary embodiment may provide a viewingangle beyond the integrated binocular display panel 200 described above.

FIG. 13A is a schematic perspective view of an integrated binoculardisplay panel according to an exemplary embodiment. FIGS. 13B and 13Care cross-sectional views of the integrated binocular display panel ofFIG. 13A.

A display panel 270 illustrated in FIGS. 13A to 13C includes both leftand right eye display areas.

In addition, the display panel 270 has a dome shape. More specifically,the display panel 270 includes a planar portion 271, and curved portions272 to 275 on the left and right sides and the upper and lower sides ofthe planar portion 271. A radius of curvature and a central angle of theleft and right curved portions 272 and 273 may be substantially the sameor different from a radius of curvature and a central angle of the upperand lower curved portions 274 and 275. The specific shape of the curvedportion and the image reduction ratio of the curved portion to theplanar portion have already been described above, and thus, repeateddescriptions thereof will be omitted to avoid redundancy.

The left and right curved portions 272 and 273 display images that arereduced in the left and right direction, and the upper and lower curvedportions 274 and 275 display images that are reduced in the up and downdirection. However, the inventive concepts not limited thereto, and theleft and right curved portions 272 and 273 may display images that arereduced further in the up and down direction, and the upper and lowercurved portions 274 and 275 may display images that are reduced furtherin the left and right direction.

Although the display panel 270 in FIG. 10A is illustrated as having thecurved portions 272 to 275 connected to each other at corners of thedisplay panel 270, the inventive concepts are not limited thereto. Forexample, the curved portions 272 to 275 may not be connected to eachother at corners of the display panel 270, and may be opened.

In addition, in an exemplary embodiment, the planar portion 271 may havea substantially quadrangular shape. However, the inventive concepts arenot limited thereto, and the planar portion 271 may have various shapeof polygons, such as ellipses, circles, and hexagons.

FIG. 14 is a schematic perspective view of a separated binocular displaypanel according to an exemplary embodiment. Detailed descriptions ofsubstantially the same elements as those described above with referenceto FIGS. 13A to 13C will be omitted to avoid redundancy.

A display panel 280 illustrated in FIG. 14 includes a left eye displaypanel 281 and a right eye display panel 282, and each of the displaypanels 281 and 282 may be separated from each other.

In addition, each of the display panels 281 and 282 has a dome shape.That is, each of the display panels 281 and 282 includes a planarportion and a curved portion on the left and right sides and the upperand lower sides of the planar portion. Each of the display panels 281and 282 may be substantially the same as the display panel 270illustrated in FIGS. 10A to 10B except for the length in the left andright direction. In addition, the left and right curved portions of eachof the display panels 281 and 282 have a structure substantially thesame as or similar to the curved portion described above with referenceto FIGS. 7A to 8.

In addition, in an exemplary embodiment, the planar portion 281 has asubstantially quadrangular shape. However, the inventive concepts arenot limited thereto, and the planar portion 281 may have various shapeof polygons, such as ellipses, circles, and hexagons.

FIGS. 15A and 15B are schematic development views illustrating anintegrated binocular display panel according to an exemplary embodiment.The display panel 270 illustrated in FIGS. 15A and 15B includes both theleft eye and right eye display areas.

The display panel 270 may be formed by curving the flat display panelillustrated in FIG. 15A. More particularly, the curved portions 272 to275 may be formed by curving areas extending in the up and downdirection and the left and right direction from the planar portion 271to have a predetermined curvature. A corner 276 between each curvedportion may be notch-cut, so that the curved portions 272 to 275 may becurved separately. Accordingly, the display panel 270 having thedeveloped view illustrated in FIG. 15A has its corners opened.

On the other hand, each corner 276 of the developed view illustrated inFIG. 15B may be cut in a curved line. Accordingly, the curved displaypanel 270 is not opened at the corners, and each curved portion 272 to275 of the display panel 270 may be connected to each other. However,the inventive concepts are not limited thereto, and the shape of thedisplay panel may be varied. For example, the display panel may havevarious types of dome shapes in various methods.

In an exemplary embodiment, viewing areas 277 and 278 of the left eye511 and the right eye 512 may refer to the area visually recognized bythe user while the user wears the head-mounted display device. Eachviewing area 277 and 278 may have a substantially elliptical or circularshape. According to an exemplary embodiment, the viewing areas 277 and278 overlap the planar portion 271 and a part of the curved portions 272to 275, and do not overlap the corner 276. That is, the corner betweenthe curved portions 272 to 275 may not be viewed by the user. Inaddition, the respective viewing areas 277 and 278 do not overlap eachother.

FIG. 16 is a schematic development view of a separated binocular displaypanel according to an exemplary embodiment. The display panel 280illustrated in FIG. 16 includes a left eye display panel 281 and a righteye display panel 282, and each of the display panels 281 and 282 may beseparated from each other.

Each of the display panels 281 and 282 may be substantially the same asthe display panel 270 illustrated in FIG. 15A except for the length inthe left and right direction. In addition, the left and right curvedportions of each of the display panels 281 and 282 have a structuresubstantially the same or similar to that of the curved portiondescribed with reference to FIGS. 10 and 11.

As described above with reference to FIG. 15A, corners between eachcurved portion are cut in the form of a quadrangle, and the corners ofthe display panel 270 having the developed view illustrated FIG. 16 areopened. In addition, the open corner may not be included in a viewingarea 283 of the left eye 511 and the right eye 512.

According to an exemplary embodiment, the corners between each curvedportion in each of the display panels 281 and 282 may be cut assimilarly in FIG. 15B, and thus, the curved portions may be connected toeach other.

In an exemplary embodiment, as illustrated in FIG. 16, each of thedisplay panels 281 and 282 may include a display area 286, in whichimages are displayed, and a non-display area 285 in the periphery, inwhich images are not displayed. In the non-display area 285, variouswirings for driving the display panels 281 and 282 may be disposed. Thenon-display area 285 may be included in all the display panels 200described above.

FIG. 17 is an enlarged view of a part of a display panel according to anexemplary embodiment. FIG. 18 is a cross-sectional view taken along lineIV-IV′ of FIG. 4.

Referring to FIGS. 17 and 18, the display panel according to anexemplary embodiment includes a plurality of pixels, each including aswitching thin film transistor, a driving thin film transistor, acapacitor, and an OLED 810. The OLED 810 may be largely applied toflexible display devices as it may be deposited at a relatively lowtemperature and has low power consumption, high luminance, and the like.As used herein, the pixel may refer to a minimum unit for displayingimages, and the display panel 200 may display images through theplurality of pixels.

Although FIG. 17 shows that one pixel includes two thin film transistorsand one capacitor, the inventive concepts are not limited thereto. Forexample, one pixel may include three or more thin film transistors andtwo or more capacitors, and may have various structures includingadditional wirings.

The display panel may include a substrate 710, a gate line 751 disposedon the substrate 710, and a data line 771 and a common power line 772insulated from and crossing the gate line 751. One pixel PX may betypically defined by the gate line 751, the data line 771 and the commonpower line 772, in which they become a boundary, but the inventiveconcepts are not limited thereto. The pixel may be defined by a pixeldefining layer or a black matrix.

The substrate 710 may include a flexible plastic material. For example,the substrate 710 may include at least one of Kapton®, polyethersulphone(PES), polycarbonate (PC), polyimide (PI), polyethyleneterephthalate(PET), polyethylene naphthalate (PEN), polyacrylate (PAR), fiberreinforced plastic (FRP), or the like.

The substrate 710 may a thickness in a range from about 5 μm to about200 μm. When the substrate 710 has a thickness less than about 5 it isdifficult for the substrate 710 to stably support the OLED 810. On theother hand, when the substrate 710 has a thickness greater than about200 flexible characteristics of the substrate 710 may be deteriorated.

A buffer layer 720 is disposed on the substrate 710. The buffer layer720 may prevent permeation of undesirable elements and to planarize asurface therebelow by including suitable materials for planarizingand/or preventing permeation. For example, the buffer layer 720 mayinclude one of a silicon nitride (SiN_(x)) layer, a silicon oxide (SiO₂)layer, and a silicon oxynitride (SiO_(x)N_(y)) layer. However, thebuffer layer 720 may be omitted depending on the kinds of the substrate710 and process conditions thereof.

A switching semiconductor layer 731 and a driving semiconductor layer732 are disposed on the first buffer layer 720. The switchingsemiconductor layer 731 and the driving semiconductor layer 732 mayinclude at least one of a polycrystalline silicon layer, an amorphoussilicon layer, and an oxide semiconductor, such as indium gallium zincoxide (IGZO) and indium zinc tin oxide (IZTO). For example, when thedriving semiconductor layer 732 includes a polycrystalline siliconlayer, the driving semiconductor layer 732 includes a channel area,which is not doped with impurities, and p+ doped source and drain areas,which are formed on opposite sides of the channel area. In such anexemplary embodiment, p-type impurities, such as boron B, may be used asdopant ions, and B₂H₆ is typically used. Such impurities may varydepending on the type of thin film transistors. The driving thin filmtransistor according to an exemplary embodiment may employ a p-channelmetal oxide semiconductor (“PMOS”) thin film transistor including p-typeimpurities, but the inventive concepts are not limited thereto. Forexample, the driving thin film transistor may employ an n-channel metaloxide semiconductor (“NMOS”) thin film transistor or a complementarymetal oxide semiconductor (“CMOS”) thin film transistor.

A gate insulating layer 740 is disposed on the switching semiconductorlayer 731 and the driving semiconductor layer 732. The gate insulatinglayer 740 may include at least one of tetraethylorthosilicate (TEOS),silicon nitride (SiN_(x)), and silicon oxide (SiO₂). For example, thegate insulating layer 740 may have a double-layer structure, in which aSiN_(x) layer having a thickness of about 40 nm and a TEOS layer havinga thickness of about 80 nm are sequentially stacked.

A gate wiring, which includes gate electrodes 752 and 755 is disposed onthe gate insulating layer 740. The gate wiring further includes the gateline 751, a first capacitor plate 758, and other signal lines. Inaddition, the gate electrodes 752 and 755 are disposed to overlap atleast a portion of the corresponding semiconductor layers 731 and 732,for example, a channel area thereof. The gate electrodes 752 and 755 maysubstantially prevent impurities from being doped into the channel areaof the corresponding semiconductor layers 731 and 732, when the impurityis doped into a source area and a drain area of the semiconductor layer731 and 732, respectively.

The gate electrodes 752 and 755 and the first capacitor plate 758 aredisposed on a substantially same layer and include a substantially samemetal material. The gate electrodes 752 and 755 and the first capacitorplate 758 may include at least one of molybdenum (Mo), chromium (Cr),and tungsten (W).

An insulating interlayer 760 is disposed on the gate insulating layer740 to cover the gate electrodes 752 and 755. The insulating interlayer760, similar to the gate insulating layer 740, may include or be formedof silicon nitride (SiN_(x)), silicon oxide (SiO_(x)), tetraethoxysilane(TEOS), or the like, but the inventive concepts are not limited thereto.

A data wiring, which includes source electrodes 773 and 776 and drainelectrodes 874 and 777, is disposed on the insulating interlayer 760.The data wiring further includes the data line 771, the common powerline 772, a second capacitor plate 778, and other wirings. In addition,the source electrodes 773 and 776 and the drain electrodes 774 and 777are connected to a source area and a drain area of the correspondingsemiconductor layers 731 and 732, respectively, through a contact holedefined at the gate insulating layer 740 and the insulating interlayer760.

As such, the switching thin film transistor includes the switchingsemiconductor layer 731, the switching gate electrode 752, the switchingsource electrode 773, and the switching drain electrode 774, and thedriving thin film transistor includes the driving semiconductor layer732, the driving gate electrode 755, the driving source electrode 776,and the driving drain electrode 777. However, the inventive concepts arenot limited thereto, and configurations of the thin film transistors maybe modified into various structures.

In addition, the capacitor includes the first capacitor plate 758 andthe second capacitor plate 778 with the insulating interlayer 760therebetween.

The switching thin film transistor may function as a switching elementto select pixels to perform light emission. The switching gate electrode752 is connected to the gate line 751. The switching source electrode773 is connected to the data line 771. The switching drain electrode 774is spaced apart from the switching source electrode 773 and is connectedto the first capacitor plate 758.

The driving thin film transistor applies, to a pixel electrode 811, adriving power which allows a light emitting layer 812 of an OLED 810 ina selected pixel to emit light. The driving gate electrode 755 isconnected to the first capacitor plate 758. Each of the driving sourceelectrode 776 and the second capacitor plate 778 is connected to thecommon power line 772. The driving drain electrode 777 is connected tothe pixel electrode 811 of the OLED 810 through a contact hole.

With the aforementioned structure, the switching thin film transistor isdriven by a gate voltage applied to the gate line 751 and serves totransmit a data voltage, applied to the data line 771, to the drivingthin film transistor. A voltage equivalent to a difference between acommon voltage applied to the driving thin film transistor from thecommon power line 772, and the data voltage transmitted from theswitching thin film transistor is stored in the capacitor, and a currentcorresponding to the voltage stored in the capacitor flows to the OLED810 through the driving thin film transistor, and thus the OLED 810 mayemit light.

A planarization layer 765 is disposed to cover the data wiring, e.g.,the data line 771, the common power line 772, the source electrodes 773and 776, the drain electrodes 774 and 777, and the second capacitorplate 778, which are patterned into a substantially same layer on theinsulating interlayer 760.

The planarization layer 765 may substantially eliminate a stepdifference of a structure therebelow and planarize a surface therebelow,which may increase luminous efficiency of the OLED 810 to be formedthereon. The planarization layer 765 may include at least one of apolyacrylate resin, an epoxy resin, a phenolic resin, a polyamide resin,a polyimide resin, an unsaturated polyester resin, a polyphenylen etherresin, a polyphenylene sulfide resin and benzocyclobutene (BCB).

The pixel electrode 811 of the OLED 810 is disposed on the planarizationlayer 765. The pixel electrode 811 is connected to the drain electrode777 through a contact hole defined at the planarization layer 765.

A pixel defining layer 790, which exposes at least a portion of thepixel electrode 811 to define a pixel area, is disposed on theplanarization layer 765. The pixel electrode 811 is disposed tocorrespond to the pixel area defined by the pixel defining layer 790.The pixel defining layer 790 may include a resin based on, for example,polyacrylate and polyimide.

The light emitting layer 812 is disposed on the pixel electrode 811 inthe pixel area, and a common electrode 813 is disposed on the pixeldefining layer 790 and the light emitting layer 812. The light emittinglayer 812 includes a low molecular organic material or a high molecularorganic material. At least one of a hole injection layer HIL and a holetransport layer HTL may further be disposed between the pixel electrode811 and the light emitting layer 812, and at least one of an electrontransport layer ETL and an electron injection layer EIL may further bedisposed between the light emitting layer 812 and the common electrode813.

The pixel electrode 811 and the common electrode 813 may be formed asone of a transmissive electrode, a transflective electrode and areflective electrode.

Transparent conductive oxide (“TCO”) may be used to form a transmissiveelectrode. TCO may include indium tin oxide (ITO), indium zinc oxide(IZO), zinc oxide (ZnO), indium oxide (In₂O₃), of the like.

Metal, e.g., magnesium (Mg), silver (Ag), gold (Au), calcium (Ca),lithium (Li), chromium (Cr), aluminum (Al), and copper (Cu), or an alloythereof may be used to form a transflective electrode and a reflectiveelectrode. In such an exemplary embodiment, whether an electrode is atransflective type or a reflective type depends on the thickness of theelectrode. Typically, the transflective electrode has a thickness ofabout 200 nm or less, and the reflective electrode has a thickness ofabout 300 nm or more. As the thickness of the transflective electrodedecreases, light transmittance and resistance may increase. On thecontrary, as the thickness of the transflective electrode increases,light transmittance may decrease.

In addition, the transflective electrode and the reflective electrodemay have a multilayer structure, which includes a metal layer includingmetal or an alloy thereof, and a TCO layer stacked on the metal layer.

An encapsulation layer 850 is disposed on the common electrode 813. Theencapsulation layer 850 includes one or more inorganic layers 851 and853 and one or more organic layers 852. In addition, the encapsulationlayer 850 has a structure, in which the inorganic layers 851 and 853 andthe organic layers 852 are laminated alternately with each other. Insuch an exemplary embodiment, the inorganic layer 851 is disposed at alowermost portion. That is, the inorganic layer 851 is disposed mostadjacent to the OLED 810.

In FIG. 18, the encapsulation layer 850 according to an exemplaryembodiment is illustrated as including two inorganic layers 851 and 853and one organic layer 852, but the inventive concepts are not limitedthereto.

The inorganic layers 851 and 853 include one or more inorganic materialsof Al₂O₃, TiO₂, ZrO, SiO₂, AlON, AlN, SiON, Si₃N₄, ZnO, and Ta₂O₅. Theinorganic layers 851 and 853 may be formed through methods, such as achemical vapor deposition (CVD) method or an atomic layer deposition(ALD) method. However, the inventive concepts are not limited thereto,and the inorganic layers 851 and 853 may be formed through variousmethods generally known in the art.

The organic layer 852 may include or be formed of a polymer material.Examples of the polymer material may include, for example, an acrylicresin, an epoxy resin, polyimide and polyethylene. The organic layer 852may be formed through a thermal deposition process. The thermaldeposition process for forming the organic layer 852 may be performed ina range of temperature that may not damage the OLED 810. However, theinventive concepts are not limited thereto, and the organic layer 852may be formed through various methods generally known in the art.

The inorganic layers 851 and 853, which have a high density of thinfilm, may substantially prevent or efficiently reduce permeation of,mostly, moisture or oxygen. Permeation of moisture and oxygen into theOLED 810 may be largely prevented by the inorganic layers 851 and 853.

The encapsulation layer 850 may have a thickness of about 10 μm or less.Accordingly, an overall thickness of the display panel may becomesignificantly small. By applying such an encapsulation layer 850, thedisplay panel may have optimized flexible characteristics.

A protective film 400 is disposed below the substrate 710. Theprotective film 400 may be attached to a lower portion of the substrate710 through an adhesive. The protective film 400 may improve thestrength of the display panel and substantially prevent the displaypanel from being damaged.

The protective film 400 may include a flexible plastic material. Inaddition, the protective film 400 may have various thicknesses dependingon Young's modulus. The protective film 400 according to an exemplaryembodiment may have a substantially same shape as that of the substrate710.

FIGS. 19A and 19B are development views illustrating a display panelaccording to exemplary embodiments.

Referring to FIG. 19A, the display panel 200 according to an exemplaryembodiment may include a planar portion 210 and a curved portion 220disposed at opposite sides of the planar portion 210, for example, onthe left or right sides or on the upper and lower sides. Referring toFIG. 19B, the display panel 200 according to an exemplary embodiment mayinclude the planar portion 210 and the curved portion 220 disposed onthe left and right sides and on the upper and lower sides.

As illustrated in FIG. 19A, in the display panel 200 according to anexemplary embodiment, the curved portion 220 has a resolution higherthan that of the planar portion 210. As used herein, the resolution mayrefer to the number of pixels PX per unit area or unit length.Accordingly, the pixels are disposed more densely in the curved portion220.

According to an exemplary embodiment, the resolution of the curvedportion 220 in the left and right direction (the number of pixels PX perunit length in the left and right direction) is higher than theresolution of the planar portion 210. In addition, according to anexemplary embodiment of the present invention, the resolution of thecurved portion 220 in the up and down direction (the number of pixels PXper unit length in the up and down direction) is higher than theresolution of the planar portion 210.

A ratio R2/R1 of the resolution R2 of the curved portion 220 to theresolution R1 of the planar portion 210 corresponds to the reciprocal ofthe image reduction ratio described hereinabove with reference to FIGS.4 to 8. That is, as the resolution becomes higher, the displayed imagemay be reduced to a greater extent. Accordingly, detailed descriptionsof the resolution ratio R2/R1 will be omitted.

In an exemplary embodiment, as described above with reference to FIGS.17 and 18, the display panel 200 may include the gate line 751extending, for example, in the left and right direction and the dataline 771 extending, for example, in the up and down direction. One pixelmay be defined by one of the gate lines 751 and one of the data lines771, and may be defined by these lines 751 and 771.

In an exemplary embodiment, an interval between the data lines 771, inthe left and right curved portion 220 of the display panel 200illustrated in FIG. 19A, which extend substantially in parallel in theup and down direction, may be decreased, as is disposed further awayfrom the planar portion 210. Accordingly, the image displayed on thecurved portion 220 may be reduced more in the left and right direction,as it is positioned further away from the planar portion 210.

In an exemplary embodiment, an interval between the gate lines 751, inthe left and right curved portion 220 of the display panel 200illustrated in FIG. 19A, which extend substantially in parallel in theleft and right direction, may be decreased, as is disposed further awayfrom the planar portion 210. Accordingly, the gate line 751 that passesthrough the center (a point most adjacent to the viewing point 420) ofthe planar portion 210 extends in a straight line even in the curvedportion 220, but the gate line 751 that passes through upper and lowersides of the planar portion 210 may be curved in the curved portion 220more toward the gate line 751 that passes through the center, as isdisposed further away from the planar portion 210. Accordingly, theimage displayed on the curved portion 220 may be reduced more in the upand down direction, as is positioned further away from the planarportion 210.

In an exemplary embodiment, in FIG. 19B, the gate line 751 and the dataline 771 disposed in the curved portion on the upper and lower sides ofthe planar portion are disposed similarly to the data line 771 and thegate line 751 disposed in the curved portion on the left and right sidesof the planar portion 210.

That is, an interval between the gate lines 751, in the upper and lowercurved portion 220, which extend substantially in parallel in the leftand right direction, may be decreased, as is disposed further away fromthe planar portion 210. In addition, an interval between the data lines771, in the upper and lower curved portion 220, which extendsubstantially in parallel in the up and down direction, may bedecreased, as is disposed further away from the planar portion 210.Accordingly, the data line 771 that passes through the center (a pointmost adjacent to the viewing point 420) of the planar portion 210extends in a straight line even in the curved portion 220, but the dataline 771 that passes through left and right sides of the planar portion210 may be curved in the curved portion 220 more toward the data line771 that passes through the center, as is positioned further away fromthe planar portion 210.

In addition, as described above, as the interval between the gate lines751 and the interval between the data lines 771 decreases, a planar areaof the pixel PX may be reduced. That is, a planar area of the pixel PXdisposed at the curved portion 220 may decrease, as is disposed furtheraway from the planar portion 210.

Accordingly, in the illustrated exemplary embodiment, a reduced imagemay be displayed on the curved portion 220 without image conversion(partial reduction) by the controller 30.

In FIGS. 19A and 19B, although the head-mounted display device isdescribed as a separated binocular display panel, the above-describedexemplary embodiments may be applied to the left eye display area andthe right eye display area of the integrated binocular display panel.

According to one or more exemplary embodiments, the head-mounted displaydevice may provide an improved viewing angle. In addition, thehead-mounted display device according to exemplary embodiments mayreduce distortion of the image viewed by the user.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of theappended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. A display device comprising: a display panel comprising a planar portion and a curved portion extending from the planar portion; and a controller to provide a data signal representing an image to be displayed on the planar portion and the curved portion to the display panel, wherein the controller is configured to provide a data signal representing an image that is reduced at a greater extent to a portion of the curved portion that is disposed further away from the planar portion, and wherein the display device is a head-mounted display device.
 2. The display device of claim 1, further comprising: a case part on which the display panel is mounted; a cushion part disposed between the case part and a wearer; and a strap part coupled to the case part, wherein the case part, the cushion part, and the strap part define a viewing point of the wearer with respect to the display panel
 3. The display device of claim 1, further comprising a sensor to measure a viewing point of a wearer with respect to the display panel.
 4. The display device of claim 1, further comprising an optical system spaced apart from the display panel by a predetermined distance.
 5. The display device of claim 1, wherein: the display panel comprises a left eye display panel and a right eye display panel arranged in the left and right direction with respect to a wearer; and each of the left eye display panel and the right eye display panel comprises a planar portion and a curved portion.
 6. The display device of claim 5, wherein the left eye display panel and the right eye display panel are separated by a protrusion disposed therebetween.
 7. The display device of claim 5, wherein each of the curved portions of the left eye display panel and the right eye display panel comprises a left curved portion disposed on a left side of the planar portion and a right curved portion disposed on a right side of the planar portion.
 8. The display device of claim 1, wherein the reduced image is substantially the same as an image that is not reduced on a virtual plane extending from the planar portion, when viewed from a wearer's viewing point.
 9. A display device comprising: a display panel comprising a first electrode, a second electrode, and an organic light emitting layer between the first and second electrodes, the display panel having a planar portion and a curved portion extending from the planar portion; and a controller to provide a data signal representing an image to be displayed on the planar portion and the curved portion to the display panel, wherein the controller is configured to provide a data signal representing an image that is reduced at a greater extent to a portion of the curved portion that is disposed further away from the planar portion.
 10. The display device of claim 9, wherein the display panel comprising: a substrate comprising a planar portion and a curved portion; a planarization layer on the substrate, the first electrode being disposed on the planarization layer; and a pixel defining layer disposed on the planarization layer and exposing at least a portion of the first electrode to define a pixel area.
 11. The display device of claim 9, wherein the curved portion comprising: first curved portions disposed on opposite sides of the planar portion in a first direction; and second curved portions disposed on opposite sides of the planar portion in a second direction substantially perpendicular to the first direction.
 12. The display device of claim 11, wherein the controller is configured to provide a data signal representing an image that is reduced in the first direction to the first curved portions and provide a data signal representing an image that is reduced in the second direction to the second curved portions.
 13. The display device of claim 11, wherein the reduced image is substantially the same as an image that is not reduced on a virtual plane extending from the planar portion, when viewed from a wearer's viewing point.
 14. A display device comprising: a display panel comprising a planar portion and a curved portion extending from the planar portion, the curved portion comprising first curved portions disposed on opposite sides of the planar portion in a first direction and second curved portions disposed on opposite sides of the planar portion in a second direction substantially perpendicular to the first direction; and a controller to provide a data signal representing an image to be displayed on the planar portion and the curved portion to the display panel, wherein the first curved portions and the second curved portions are spaced apart from each other at a corner of the planar portion.
 15. The display device of claim 14, wherein the corner of the planar portion is not visually recognized by a wearer.
 16. The display device of claim 14, wherein the controller is configured to provide a data signal representing an image that is reduced at a greater extent to a portion of the curved portion that is disposed further away from the planar portion.
 17. The display device of claim 14, wherein the controller is configured to provide a data signal representing an image that is reduced in the first direction to the first curved portions.
 18. The display device of claim 17, wherein the controller is configured to provide a data signal representing an image that is reduced in the second direction to the second curved portions.
 19. The display device of claim 17, wherein: the ratio of the entire curved portion is A/L, where “A” is a length of the curved portion in the first direction and “L” is a length of an equivalent area of the curved portion in the first direction; and the equivalent area is on a virtual plane extending from the planar portion, and provides a viewing angle substantially the same as a viewing angle of the curved portion in the first direction when viewed from a wearer's viewing point.
 20. The display device of claim 19, wherein the ratio of the entire curved portion is A/L, which is represented as the following Equation, $\begin{matrix} {{\frac{A}{L} = \frac{\theta\left\lbrack {1 - {\left( {R/D} \right)\left( {1 - {\cos\;\theta}} \right)}} \right\rbrack}{{\left( {B/D} \right)\left( {1 - {\cos\;\theta}} \right)} + {\sin\;\theta}}},} & \lbrack{Equation}\rbrack \end{matrix}$ where “R” is a radius of curvature of the curved portion, “θ” is a central angle of the curved portion, “D” is a distance between the viewing point of a wearer and the planar portion, and “B” is a distance in the first direction between a normal line of the planar portion that passes through the viewing point and a point where the planar portion and the curved portion meet.
 21. The display device of claim 14, wherein one side of the curved portion contacts the planar portion tangentially. 